Since 2011, the American College of Radiology’s Dose Index Registry (DIR)
has helped clinicians and facilities improve the quality of patient care by collecting CT dose indices through automated data transmission and leveraging that data to provide feedback to participants and establish national benchmarks.
The ACR’s largest registry, the DIR has data on more than 50 million exams from more than 2,100 facilities as of April 2018. After anonymization at the site, exam data are transmitted automatically from CT scanners, reducing errors while collecting data daily.
The DIR automatically aggregates data not readily available elsewhere. In addition to CTDIvol and Dose Length Product (DLP) values, the DIR also computes size-specific dose estimate values (SSDE), for body examinations, that more accurately represent the radiation dose actually absorbed by the patient, based on patient size. Exam descriptions are standardized, using RadLex Playbook procedure names, so that data are comparable across facilities and scanners. And, the large volume of data allows the DIR to provide feedback reports segmented by adult and pediatric populations, with pediatric data segmented into five distinct age groups.
The DIR has already helped improve patient care nationally through the ACR’s development of size-specific Diagnostic Reference Levels (DRLs) and Achievable Dose (AD) guidelines for the 10 most common adult CT examinations. The first such guidance for this population, radiologists can now use DRLs and ADs, based on size, to avoid giving unnecessary radiation exposure to patients. And, because data are collected automatically, updates and new analyses can be completed far faster and more economically than with manual data collection.
The DIR also provides direct feedback to facilities through quarterly reports that provide peer comparisons of each standardized exam name by
facility type (e.g. Freestanding vs. Community hospital)
location (Metropolitan, Suburban, or Rural), and
geography.
Comparisons allow facilities to identify dose outliers, by exam, so they can focus on reducing radiation exposure while maintaining image quality. 
Credit and Recognition
The DIR is certified as a Practice Quality Improvement (PQI) project for American Board of Radiology Maintenance of Certification (MOC) Part IV Programs. Because DIR data are collected at the facility level, participation applies to all radiologists and medical physicists at a facility who choose to participate in the project.
The DIR also helps facilities qualify for designation as an ACR Diagnostic Imaging Center of Excellence (DICOE), allowing radiology practices to communicate their dedication to, and success in, delivering superior diagnostic imaging and patient care.
And, DIR participation meets the Joint Commission dose benchmark requirement.